At the University of Michigan in Ann Arbor, the Diag (/ˈdaɪ.æɡ/DY-ag) is a large open space in the middle of the university's Central Campus. Originally known as the Diagonal Green, the Diag derives its name from the many sidewalks running near or through it in diagonal directions. It is one of the busiest sites on the university campus, hosting a variety of events including outdoor concerts, fundraisers, demonstrations, and sun bathing.

A brass block "M", a symbol of the university, is embedded at the center of the Diag. Local legend has it that if a UM student steps on the M before taking his or her first blue book exam at the university, the student will go on to fail that exam. The only way to reverse this "curse" was to run naked from the campus belltower during the strokes of midnight to two statues of pumas at the Natural Science Museum, then back to the tower before it stopped ringing. This has been made considerably more difficult in recent years as the belltower no longer rings at midnight.

In April 2008, spring commencement ceremonies were held at the Diag for the first time in the university's 191-year history, as the traditional commencement ceremony location, Michigan Stadium, was undergoing construction.[1]Rynearson Stadium, located at nearby Eastern Michigan University, was initially chosen by UM administration as the alternate commencement site, but a large volume of complaints led an alternate commencement site to be chosen, finally settling on the Diag.